Polyvinyl chloride compositions



Patentecl Mar. 28, 1950 POLYVINYL CHLORIDE COMPOSITIONS Joseph RaymondDarby, Richmond Heights, Mo., assignor to Monsanto ChemicaLCompany, St.Louis, Mo., a corporation of Delaware No Drawing. Application March 11,1947,

- Serial No. 733,981

9 Claims. (Cl. 260-318) Thislnvention relates to novel comprising vinylreslnscontaining predominantly polymerized vinyl chloride and diphenylphthalate. More particularly, this invention relates to polymerizedvinyl chloride resin compositions which have reduced fusion temperaturesand which compositions show only an insignificant amount ofplasticization at ordinary temperatures.

Polyvinyl resins, particularly polyvinyl chloride and the copolymerresins, polyvinyl chloride-acetate formed by the conjoint polymerizationof vinyl chloride and vinyl acetate, are normally rigid and brittle intheir unplasticized state. Although unplasticized polyvinyl chloride hasan indefinite flexibility point of approximately 75 to 80 0., asestimated by the method for determining flexibility points of plasticmaterials described by Clash and Berg, Ind. Eng. Chem., 34, 1218 (1942),the unplasticized resins do not become fused, fluid, pliable, mobile orworkable up to temperatures of 165-175 C. where thermal decomposition ofthe resins is evident. Moreover, because of the fact thatthese polyvinylresins do not have definite fusion points and do not become fluid attemperatures below their decomposition temperatures, the unplasticizedresins cannot be processed by roll-milling, extruding, or molding, andparticularly, these unplasticized resins cannot be used as the materialsfor injection molding techniques.

.To overcome many of these diificulties, it is common practice tointimately mixpolyvinyl chloride resins with plasticizing compounds suchas dioctyl phthalate, dibutyl sebacate and tricresyl phosphate. Theseplasticized compositions are easily and readily worked on-roll mills,and films and sheets formed therefrom are supple and flexible, thesecharacteristics being highly desirable for many applications. Thesecompositions may also be readily molded or extruded, although thesemolded or extruded articles possess a softness, flexibility ornon-rigidity, which are undev sirable properties for many moldedarticles.

It is an object of this invention to provide polyvinyl chloridecompositions, and compositions of vinyl resins containing predominantlypolyvinyl chloride, having reduced fusion points and, therefore, becomefused and fluid upon heating. Thus these new compositions may be readilymilled, molded or extruded, but these new compositions, when cooled toordinary temperatures,

have the rigidity, hardness and other appearance 'ofthe unplasticizedpolymerized vinyl resin.

I have discovered that when a composition is compositions 2 preparedcomprising polyvinyl chloride and diphenyl phthalate or polyvinylchloride-acetate and diphenyl phthalate, the diphenyl phthalate acts toreducethe fusion temperature of the polyvinyl chloride resins and thecomposition fuses and becomes mobile, viscous or fluid at the usualmilling and molding temperatures of 110 to 165 C. Moreover, upon coolingto ordinary temperatures the compositions become hard, rigid, tough,non-extensible and have all the appearances of an unplasticizedpolyvinyl chloride resin and indicate only an insignificant amount ofplastlcization by the diphenyl phthalate.

The invention thus provides for the fabrication of hard, rigid and solidarticles from polyvinyl chloride resins. Thus, a composition comprisinga polyvinyl chloride resin and diphenyl phthalate may be worked smoothlyand easily upon a differential-speed, two-roll mill while in a fiuxedand fused state, and yet, upon removing the sheet from the roll mill andcooling it to room temperature, there will result a hard, boardy,non-extensible and rigid sheet which will exhibit practically noevidence of plasticization. In addition, this discovery facilitates theuse of injection molding techniques to form, from polyvinyl chlorideresins, hard, rigid and fracture resistant molded articles of intricatedesign and sharp impression, since the fluid composition comprising thepolyvinyl chloride resin and diphenyl phthalate fills the crevices andintricacies of the mold in a manner which is not obtainable withunplasticized polyvinyl chloride, but yet, the finished article has allthe appearances and most of the proper- ,ties of an unplasticizedpolyvinyl chloride resin,

particularly, hardness and rigidity.

This invention is particularly applicable to polymerized vinyl chlorideresins and to resins formed by the conjoint polymerization of vinylchloride with other materials such as vinyl acetate, vinyl propionate,vinylidene chloride, methyl methacrylate or diethyl maleate, preferablywhen vinyl chloride comprises at least 85% of the copolymer resin. I

The diphenyl phthalate may be incorporated into the vinyl resincompositions in amounts up to 40% by weight of the composition. However,a composition containing 10 to 35% by weight of diphenyl phthalate andpreferably 15 to 30% by weight, is desirable for most purposes. In theplasticized resin art the plasticizer content of a resinous compositionis more frequently expressed on the basis of parts by weight ofplasticizer per 100 parts of resin. According to this mode ofexpression, the above expressed percentage comthe rolls.

. positions, approximate to 55 parts by weight of diphenyl phthalate per100 parts of resin and preferably to 45 parts by weight of diphenylphthalate per 100 parts of resin as compositions being desirable formost purposes. The diphenyl phthalate may also be used in conjunctionwith compositions containing polymerized vinyl chloride and conventionalplasticizers, however, these compositions containing diphenyl phthalatewill have properties evidencing plasticization to the extent of theconventional plasticizer employed.

Other phthalates were investigated in connection with this invention,and all acted to produce rubbery, supple or flexible compositions whenthe phthalates were present in suflicient amounts to facilitate millingor molding operations.

For example, a composition containing 70% polyvinyl chloride and 30%dibenzyl phthalate, when worked on a roll mill at 165 C. until ahomogeneous composition is formed, produces a sheet which is flexible atnormal temperatures.

In a similar manner, a composition containing 70% polyvinyl chloride and30% butyl benzyl phthalate gives a flexible sheet at normal temperature.The plasticizing action of dioctyl phthalate on polyvinyl chloride toproduce supple plastic compositions is well known to the Example I 100parts by weight of a polymerized vinyl chloride resin were intimatelymixed with parts by weight of diphenyl phthalate, and the mixture wasworked on a dilferential speed tworoll mill, wherein the temperature ofone roll was maintained at 160 C. and the other roll at 145 0., until ahomogeneous compositoin was formed. At this milling temperature, thediphenyl phthalate caused the polymerized vinyl chloride resin to flux,and work very easily and smoothly on A sheet was removed from the rollsand cooled to room temperature.

At room temperature, the finished sheet was hard, tough, boardy andrigid and had all the appearances of an unplasticized polyvinyl chloridecomposition.

The flexibility point was determined and was found to be about 44 C.

This example illustrates the action of the diphenyl phthalate inlowering the fusion point of polyvinyl chloride resins. However, thehigh temperature at which the composition begins to lose its rigiditycharacteristic indicates that diphenyl phthalate at ordinarytemperatures has but a very slight plasticizing action on polyvinylchloride resins, and the composition at normal temperatures is rigid.

Example II was removed from the rolls and cooled to room temperature.

At room temperature, the finished sheet was hard, tough, boardy andrigid and exhibited properties which were substantially the same as anunplasticized polyvinyl chloride/resin.

The flexibility point was determined and was found to be about 34 C.

This example illustrates the action of the diphenyl phthalate inlowering the fusion point of polyvinyl chloride resins. However, thehigh temperature at which the composition containing diphenyl phthalatebegins to lose its rigidity characteristic indicates that diphenylphthalate at ordinary temperatures has but a very slight plasticizingaction on polyvinyl chloride resins, even when present to the extent of30% of the composition.

Example III 100 parts by weight of a polyvinyl chloride resin formed bythe copolymerization of vinyl chloride and vinyl acetate wherein thevinyl chloride comprises by weight of the copolymer resin, wereintimately mixed with 54 parts by weight of diphenyl phthalate and onepart of lead silicate, a heat stabilizer, and the mixture was fused andworked on a differential-speed two-roll mill,;wherein one roll wasmaintained at a temperature of 160 C. and the other roll at 0., until ahomogeneous composition was formed. At this milling temperature thediphenyl phthalate caused the copolymer vinyl chloride-acetate resin toflux and become mobile on the rolls. The sheet was removed from therolls and cooled to room temperature. At room temperature this finishedsheet comprising approximately 35% diphenyl phthalate and 65% of thecopolymer vinyl chloride-acetate resin was hard, boardy and rigid.

Example IV .100 parts by weight of polymerized vinyl chloride and 43parts by weight of diphenyl phthalate were mixed together and heated toC. in a heated mixing machine until the mixture fluxed and a homogeneouscomposition was formed. This mobile composition was then transferred toan injection molding machine, heated to approximately C. and was thenformed by means of an injection molding technique into an article in theshape of a golf tee.

Upon cooling and removing the golf tee from the mold, it was found to bevery rigid, hard and fracture resistant and appeared to be an articlemolded from unplasticized polyvinyl chloride. Moreover, the designs andinscriptions of the mold were sharply and perfectly formed upon the golftee.

Example V 100 parts by weight of a vinyl resin formed by thecopolymerization of vinyl chloride and vinylidine chloride wherein thevinyl chloride comprises 85% by weight of the copolymer resin,

were intimately mixed at 150 C.'with 54 parts by weight of diphenylphthalate until the mixture fused and a homogeneous composition wasformed. The composition was cooled and a molding powder preparedtherefrom. The powdered composition was placed in a pressure moldingapparatus, heated to approximately 160 C. and formed into an article ofthe shape of a dumbbell.

Upon cooling and removing the dumbbell from the mold, it was found to bevery rigid and hard,

and had the apparent characteristics of an article molded from theunplasticized copolymer resin.

I claim:

1. A composition capable of fusing under heat, comprising a polymerizedvinyl resin containing at least 85% of combined vinyl chloride, andcontaining to 55 parts by weight of diphenyl phthalate per 100 parts ofsaid resin.

2. A composition capable of fusing under heat, comprising polyvinylchloride and 10 to 55 parts by weight of diphenyl phthalate per 100parts of polyvinyl chloride.

3. A composition capable of fusing under heat, comprising polyvinylchloride and 20 to 45 parts of diphenyl phthalate per 100 parts ofpolyvinyl chloride.

4. A composition capable of fusing under heat, comprising a polymerizedvinyl resin which is a conjoint polymer of vinyl chloride and vinylacetate, wherein the vinyl chloride comprises at least 85% of theconjoint polymer, and 10 to 55 parts by weight of diphenyl phthalate per100 parts of said resin.

5. A composition capable of fusing under heat, comprising a polymerizedvinyl resin which is a conjoint polymer of vinyl chloride and vinylidinechloride wherein the vinyl chloride comprises at least 85% of theconjoint polymer, and 10 to 55 parts by weight of diphenyl phthalate per100 parts of said resin.

6. A method for making solid, hard and rigid compositions containingpolymerized vinyl chloride and having relatively low fusiontemperatures, comprising intimately mixing a polymerized vinyl resincontaining at least 85% of combined vinyl chloride at an elevatedtemperature within the range of substantially 110 to 175 C. with 10 to55 parts by weight of a fusion temperature lowering agent consisting ofdiphenyl phthalate per 100 parts of said vinyl resin and thereby forminga fused mixture, cooling said mixture below the softening point of thecomposition and thereby forming a solid, hard and rigid composition;said composition being normally and substantially of the same hardnessand rigidity as said resin, and said composition fusing at a lowertemperature than said resin.

7. A method of forming solid, hard and rigid articles of manufacturecontaining predominantly polyvinyl chloride, comprising fusing polyvinylchloride at an elevated temperature within the range'of substantially110 to 175 C. with 10 to 55 parts by weight of diphenyl phthala parts ofsaid vinyl resin, fusing said mixture atperioopartsofpolyvinylchloridetoforma an elevated temperature within therange of substantially 100 to 175 C., forming said fused mixture in apredetermined shape and causing said mixture to harden in thepredetermined shape by cooling below the softening point of thecomposition; said article having normally substan tially the samehardness and rigidity as said resin, and said article having a lowerfusion temperature than said resin.

9. A method of forming solid, hard and rigid articles of manufacturefrom a vinyl resin which is the conjoint polymer of vinyl chloride andvinylidine chloride, wherein the vinyl chloride comprises at least ofthe conjoint polymer, comprising intimately mixing said resin with 10 to55 parts by weight of a fusion temperature lowering agent consisting ofdiphenyl phthalate per parts of said vinyl resin, fusing said mixture atan elevated temperature within the range of substantially to 0., formingsaid fused mixture in a predetermined shape, and cooling said mixturebelow the softening point of the composition while retaining in saidpredetermined shape; said article having normally substantially the samehardness and rigidity as said resin, and said article having a lowerfusion temperature than said resin.

JOSEPH RAYMOND DARBY.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS OTHER REFERENCES Film Forming Plastics," articleby aemnm et al., Industrial and Engineering Chemistry, vol. 31 N0. 12December 1939, M88 1522-1529.

1. A COMPOSITION CAPABLE OF FUSING UNDER HEAT, COMPRISING A POLYMERIZEDVINYL RESIN CONTAINING AT LEAST 85% OF COMBINED VINYL CHLORIDE, ANDCONTAINING 10 TO 55 PARTS BY WEIGHT OF DIPHENYL PHTHALATE PER 100 PARTSOF SAID RESIN.